1. Field of the Invention
This invention relates to an external information storage device for information processing equipment such as computers and word processors, and more particularly to a drive apparatus for driving an information recording medium encased in a cartridge having a hard case when recording data onto the recording medium or when reading data from the recording medium.
2. Description of the Prior Art
Recently, the demand for floppy disk devices as computer external storage devices have been repidly increasing because the floppy disk is cheap, easy to handle and is easily attachable to and detachable from a drive apparatus. The latest portable personal computers and word processors have built-in floppy disk storage devices. Since such portable equipment is required to be smaller in size and lighter in weight, a small and low profile storage device is strongly needed.
Floppy disk cartridges and drive apparatusses disclosed in U.S. Pat. Nos. 4,525,758 and 4,445,155 disclose typical portable information processing equipment. However, these conventional drive apparatuses are structurally difficult to reduce in size. The cartridge disclosed in U.S. Pat. No. 4,525,758 has head windows normally closed by shutters which are connected to an end of an elongated flexible band which has at the other end a protrusion exposed outside of the cartridge. The protrusion, when the cartridge is inserted into the drive apparatus, is pushed by a member fixed to the drive apparatus so that the flexible band moves to open the shutter. The cartridge must be almost fully inserted into the drive apparatus so that the protrusion can be pushed in a distance to fully open the shutter. In other words, the length of the drive apparatus (in the cartridge inserting direction) must be large enough so that the position of the fully pushed protrusion is in the drive apparatus. The cartridge disclosed in U.S. Pat. No. 4,445,155 has a notch for inhibiting data from being written onto the built-in magnetic disk. Since this notch is disposed near a rear corner of the cartridge, the cartridge must be almost fully inserted into the drive apparatus. As described above, the size of the conventional drive apparatus was limited by the standardized structure of the cartridge.
Another obstacle for reducing the size of the floppy disc drive apparatus is a pad for pushing the flexible magnetic disc against the magnetic head. Such a pad is disclosed in U.S. Pat. No. 3,678,481. The pad is fixed to an end of a rotatable arm which is rotatable about a pivot disposed at an end of a head carriage movable in the radial direction of the magnetic disk. The arm is urged in such a direction that the pad is pushed against the magnetic head so that the magnetic disk contacts the magnetic head in a proper contact condition. With this structure, however, the size of the head carriage in the longitudinal direction of the drive apparatus must be large, and thus, the drive apparatus must also be long.
An improved pad is disclosed in Japanese Laid-Open patent application No. 56-54665, in which an arm mounting the pad is rotatably mounted on the frame of the drive apparatus, and the pad is lengthened in the head moving direction. However, this structure still has the following problems. The parallel relation between the pad surface and the head surface is not maintained due to variations of the thickness of the pad, thickness of the adhesive to fix the pad, length of the arm and position of the pivot of the arm. Furthermore, the pad creeps due to high temperature or high humidity so that the pad surface becomes curved in the form of the head surface. Thus, the contact pressure exerted by the pad onto the head will not be uniform, so that reliable recording and reproduction of data will not be expected after a long period of use.